Internal combustion engines are often called upon to generate considerable levels of power for prolonged periods of time on a dependable basis. Many such internal combustion engine assemblies employ a mechanical turbocharging or supercharging device, such as a turbocharger or a turbine driven, forced induction turbocharger or supercharger, to compress the airflow before it enters the intake manifold of the engine in order to adjust power and efficiency. Specifically, a turbocharger is a gas compressor that forces more air and, thus, more oxygen into the combustion chambers of the engine than is otherwise achievable with ambient atmospheric pressure. The additional mass of oxygen-containing air that is forced into the engine improves the engine's volumetric efficiency, allowing it to burn more fuel in a given cycle, and thereby produce more power.
Under extreme operating conditions, the “turbocharging” or “supercharging” process may elevate the temperatures of the intake air to an extent that pre-determination of the fuel/air charge prior to timed spark ignition may occur and potentially damage the engine. To combat this problem, engine manufacturers have historically employed a device most commonly known as an intercooler, but more appropriately identified as a charge air cooler (CAC) or aftercooler, to extract heat from the air exiting the turbocharging or supercharging device. A CAC is a heat exchange device used to cool the air charge and, thus, further improve volumetric efficiency of the engine by increasing intake air charge density through cooling. A decrease in air intake temperature provides a denser intake charge to the engine and allows more air and fuel to be combusted per engine cycle, increasing the output of the engine.
The heat exchange process can cause moisture to condense and, thus, form inside the CAC system, especially when conducted in conditions where the ambient air flowing through the turbocharging or supercharging device and CAC is substantially humid, such as greater than 90% relative humidity, and if external airflow, which cools the CAC, is relatively high and internal airflow, from the turbocharger, is relatively low. The condensation may accumulate either in the CAC itself and/or downstream from the CAC, within the conduit through which the intake manifold receives the turbocharged or supercharged airflow. The liquefied condensation can be drawn into the intake manifold, such as when the driver commands an acceleration, and enters the various cylinder combustion chambers. Depending upon the configuration of the CAC and the turbocharging or supercharging devices, as well as their individual and relative packaging, the condensation may enter the combustion chambers in sufficient amounts, potentially causing the engine to misfire, leading to premature engine system component wear, such as the catalytic converter, and trigger a service engine indicator light.
Some CAC systems may include a condensate reservoir or tank configured to collect water condensation. However, accumulated condensate that is not properly evacuated from a CAC can freeze when ambient temperatures reach below freezing, affecting the operation of the CAC. In addition, there may be operating conditions with some vehicle/engine systems which may cause the engine's Positive Crankcase Ventilation (PCV) system to vent crankcase moisture directly into the Turbocharger and CAC. During cold ambient conditions, such moisture may freeze inside the CAC and cause ice accumulation inside the CAC, increasing the internal air pressure drop of the CAC and eventually restricting the engine from receiving the necessary amount of airflow. Such a condition may result in insufficient Turbo Boost pressure at the inlet to the engine, triggering a service engine indicator light.